linux-kernel - Re: [PATCH v4 0/2] arm64/mm: prevent panic on -ENOMEM in arch_add

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Message-ID: <176306032237.2459767.15705296734744226735.b4-ty@arm.com>
Date: Thu, 13 Nov 2025 18:59:03 +0000
From: Catalin Marinas <cmarinas@...nel.org>
To: Will Deacon <will@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ryan Roberts <ryan.roberts@....com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Linu Cherian <linu.cherian@....com>
Cc: Catalin Marinas <catalin.marinas@....com>,
	Anshuman Khandual <anshuman.khandual@....com>,
	Kevin Brodsky <kevin.brodsky@....com>,
	Zhenhua Huang <quic_zhenhuah@...cinc.com>,
	Dev Jain <dev.jain@....com>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Yang Shi <yang@...amperecomputing.com>
Subject: Re: [PATCH v4 0/2] arm64/mm: prevent panic on -ENOMEM in arch_add_memory()

From: Catalin Marinas <catalin.marinas@....com>

On Fri, 17 Oct 2025 10:44:35 +0530, Linu Cherian wrote:
> arch_add_memory() acts as a means to hotplug memory into a system. It
> invokes __create_pgd_mapping() which further unwinds to call
> pgtable_alloc(). Initially, this path was only invoked during early boot
> and therefore it made sense to BUG_ON() in case pgtable_alloc() failed.
> Now however, we risk running into a kernel crash if we try to hotplug
> memory into a system that is already extremely tight on available
> memory. This is undesirable and hence __create_pgd_mapping() and it's
> helpers are reworked to be able to propagate the error from
> pgtable_alloc() allowing the system to fail gracefully.
> 
> [...]

Applied to arm64 (for-next/misc), thanks!

[1/2] arm64/mm: Allow __create_pgd_mapping() to propagate pgtable_alloc() errors
      https://git.kernel.org/arm64/c/bfc184cb1ba7
[2/2] arm64/mm: Rename try_pgd_pgtable_alloc_init_mm
      https://git.kernel.org/arm64/c/1b214452b6a7

-- 
Catalin